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blind-sign: add commitment in G1

This commit is contained in:
Gijs Van Laer 2019-07-07 14:10:11 -04:00
parent de9132939a
commit 3c5237f12c
3 changed files with 138 additions and 49 deletions
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10
src/ccs08.rs
View File

@ -113,7 +113,7 @@ prove_ul method is used to produce the ZKRP proof that secret x belongs to the i
let m = E::Fr::rand(rng);
// D = H^m
let mut hm = self.com.h.clone();
let mut hm = self.com.h2.clone();
hm.mul_assign(m);
for i in 0..self.l as usize {
v.push(E::Fr::rand(rng));
@ -143,7 +143,7 @@ prove_ul method is used to produce the ZKRP proof that secret x belongs to the i
let ui = self.u.pow(i as u32);
let mut muiti = t[i].clone();
muiti.mul_assign(&E::Fr::from_str(&ui.to_string()).unwrap());
let mut aux = self.com.g.clone();
let mut aux = self.com.g2.clone();
aux.mul_assign(muiti);
D.add_assign(&aux);
}
@ -206,17 +206,17 @@ verify_ul is used to validate the ZKRP proof. It returns true iff the proof is v
}
fn verify_part1(&self, proof: &ProofUL<E>) -> bool {
let mut D = proof.comm.c.clone();
let mut D = proof.comm.c2.clone();
D.mul_assign(proof.ch);
D.negate();
let mut hzr = self.com.h.clone();
let mut hzr = self.com.h2.clone();
hzr.mul_assign(proof.zr);
D.add_assign(&hzr);
for i in 0..self.l {
let ui = self.u.pow(i as u32);
let mut muizsigi = proof.zsig[i as usize];
muizsigi.mul_assign(&E::Fr::from_str(&ui.to_string()).unwrap());
let mut aux = self.com.g.clone();
let mut aux = self.com.g2.clone();
aux.mul_assign(muizsigi);
D.add_assign(&aux);
}

74
src/cl.rs
View File

@ -6,6 +6,7 @@ extern crate rand;
use super::*;
use pairing::{CurveAffine, CurveProjective, Engine};
use rand::Rng;
use ped92::Commitment;
#[derive(Clone)]
pub struct PublicParams<E: Engine> {
@ -29,7 +30,8 @@ pub struct PublicKey<E: Engine> {
//#[derive(Clone, Serialize, Deserialize)]
#[derive(Clone)]
pub struct BlindPublicKey<E: Engine> {
pub X: E::G2,
pub X1: E::G1,
pub X2: E::G2,
pub Y1: Vec<E::G1>,
pub Y2: Vec<E::G2>,
}
@ -189,11 +191,15 @@ impl<E: Engine> BlindPublicKey<E> {
Y1.push(g1y);
Y2.push(g2y);
}
// X = g2 ^ x
let mut X = mpk.g2;
X.mul_assign(secret.x);
// X1 = g1 ^ x
let mut X1 = mpk.g1;
X1.mul_assign(secret.x);
// X2 = g2 ^ x
let mut X2 = mpk.g2;
X2.mul_assign(secret.x);
BlindPublicKey {
X: X,
X1: X1,
X2: X2,
Y1: Y1,
Y2: Y2
}
@ -216,7 +222,7 @@ impl<E: Engine> BlindPublicKey<E> {
Yt.mul_assign(message[l]);
L.add_assign(&Yt);
let mut X2 = self.X;
let mut X2 = self.X2;
X2.add_assign(&L); // X2 = X + L
let lhs = E::pairing(signature.h, X2);
let rhs = E::pairing(signature.H, mpk.g2);
@ -275,6 +281,20 @@ impl<E: Engine> BlindKeyPair<E> {
self.secret.sign(csprng, message)
}
/// sign a commitment of a vector of messages
pub fn sign_blind<R: Rng>(&self, csprng: &mut R, mpk: &PublicParams<E>, com: Commitment<E>) -> Signature<E> {
let u = E::Fr::rand(csprng);
let mut h1 = mpk.g1;
h1.mul_assign(u); // g1 ^ u
let mut com1 = com.c1.clone();
let mut H1 = self.public.X1.clone();
H1.add_assign(&com1); // (X * com ^ g)
H1.mul_assign(u); // com ^ u (blinding factor)
Signature { h: h1, H: H1 }
}
/// computes a blind signature from an existing one
pub fn blind<R: Rng>(&self, csprng: &mut R, bf: &E::Fr, signature: &Signature<E>) -> Signature<E> {
self.secret.blind(csprng, bf, signature)
@ -332,6 +352,7 @@ mod tests {
use pairing::bls12_381::{Bls12, Fr};
use rand::{SeedableRng};
use rand_xorshift::XorShiftRng;
use ped92::CSMultiParams;
#[test]
fn sign_and_verify() {
@ -390,5 +411,46 @@ mod tests {
assert_eq!(keypair.verify(&mpk,&message1, &t1,&blind_sig), false);
}
#[test]
fn blind_sign_and_verify_works() {
let mut rng = &mut rand::thread_rng();
let l = 5;
let mpk = setup(&mut rng);
let keypair = BlindKeyPair::<Bls12>::generate(&mut rng, &mpk, l);
let public_key = keypair.get_public_key(&mpk);
let mut message1 : Vec<Fr> = Vec::new();
let mut message2 : Vec<Fr> = Vec::new();
for i in 0..l {
message1.push(Fr::rand(&mut rng));
message2.push(Fr::rand(&mut rng));
}
let mut com_bases1 = vec! {mpk.g1};
com_bases1.append(&mut keypair.public.Y1.clone());
let mut com_bases2 = vec! {mpk.g2};
com_bases2.append(&mut keypair.public.Y2.clone());
let com_params = CSMultiParams { pub_bases1: com_bases1, pub_bases2: com_bases2};
let t = Fr::rand(rng);
let com = com_params.commit(rng, &message1, &t);
let signature = keypair.sign_blind(rng, &mpk, com);
let unblinded_sig = keypair.unblind(&t, &signature);
let t1 = Fr::rand(&mut rng);
assert_eq!(keypair.verify(&mpk,&message1, &t,&unblinded_sig), true);
assert_eq!(keypair.verify(&mpk,&message1, &t, &signature), true);
assert_eq!(keypair.verify(&mpk,&message2, &t,&unblinded_sig), false);
assert_eq!(keypair.verify(&mpk,&message2, &t,&signature), false);
assert_eq!(keypair.verify(&mpk,&message1, &t1,&unblinded_sig), false);
assert_eq!(keypair.verify(&mpk,&message1, &t1,&signature), false);
}
}

103
src/ped92.rs
View File

@ -5,18 +5,22 @@ use ff::Rand;
#[derive(Clone)]
pub struct CSParams<E: Engine> {
pub g: E::G2,
pub h: E::G2,
pub g1: E::G1,
pub g2: E::G2,
pub h1: E::G1,
pub h2: E::G2,
}
#[derive(Clone)]
pub struct Commitment<E: Engine> {
pub c: E::G2
pub c1: E::G1,
pub c2: E::G2
}
#[derive(Clone)]
pub struct CSMultiParams<E: Engine> {
pub pub_bases: Vec<E::G2>
pub pub_bases1: Vec<E::G1>,
pub pub_bases2: Vec<E::G2>
}
//impl<E: Engine> fmt::Display for CSParams<E> {
@ -59,9 +63,11 @@ impl<E: Engine> CSParams<E> {
Implements the setup algorithm for the Pedersen92 commitment scheme
*/
pub fn setup<R: Rng>(rng: &mut R) -> Self {
let g = E::G2::rand(rng);
let h = E::G2::rand(rng);
let csp = CSParams { g, h };
let g1 = E::G1::rand(rng);
let g2 = E::G2::rand(rng);
let h1 = E::G1::rand(rng);
let h2 = E::G2::rand(rng);
let csp = CSParams { g1, g2, h1, h2 };
return csp;
}
@ -74,15 +80,21 @@ commit(pk, msg) -> cm where
pub fn commit<R: Rng>(&self, rng: &mut R, m: E::Fr, R: Option<E::Fr>) -> Commitment<E> {
let r = R.unwrap_or(E::Fr::rand(rng));
let p = "commit -> m";
// c = g^m * h^r
let mut c = self.g.clone();
c.mul_assign(m);
let mut h = self.h.clone();
h.mul_assign(r);
c.add_assign(&h);
let mut c1 = self.g1.clone();
c1.mul_assign(m.clone());
let mut h1 = self.h1.clone();
h1.mul_assign(r.clone());
c1.add_assign(&h1);
Commitment { c }
// c = g^m * h^r
let mut c2 = self.g2.clone();
c2.mul_assign(m);
let mut h2 = self.h2.clone();
h2.mul_assign(r);
c2.add_assign(&h2);
Commitment { c1, c2 }
}
/*
@ -92,14 +104,18 @@ decommit(csp, cm, msg) -> bool where
- outputs T/F for whether the cm is a valid commitment to the msg
*/
pub fn decommit(&self, cm: &Commitment<E>, m: &E::Fr, r: &E::Fr) -> bool {
let p = "decommit -> m";
let mut dm1 = self.g1.clone();
dm1.mul_assign(m.clone());
let mut h1 = self.h1.clone();
h1.mul_assign(r.clone());
dm1.add_assign(&h1);
let mut dm = self.g.clone();
dm.mul_assign(m.clone());
let mut h = self.h.clone();
h.mul_assign(r.clone());
dm.add_assign(&h);
return dm == cm.c;
let mut dm2 = self.g2.clone();
dm2.mul_assign(m.clone());
let mut h2 = self.h2.clone();
h2.mul_assign(r.clone());
dm2.add_assign(&h2);
return dm2 == cm.c2 && dm1 == cm.c1;
}
}
@ -110,40 +126,51 @@ impl<E: Engine> CSMultiParams<E> {
a vector of messages.
*/
pub fn setup_gen_params<R: Rng>(rng: &mut R, len: usize) -> Self {
let mut p: Vec<E::G2> = Vec::new();
let mut p1: Vec<E::G1> = Vec::new();
let mut p2: Vec<E::G2> = Vec::new();
for i in 0..len {
p.push(E::G2::rand(rng));
p1.push(E::G1::rand(rng));
p2.push(E::G2::rand(rng));
}
return CSMultiParams { pub_bases: p };
return CSMultiParams { pub_bases1: p1, pub_bases2: p2 };
}
pub fn commit<R: Rng>(&self, rng: &mut R, x: &Vec<E::Fr>, r: &E::Fr) -> Commitment<E> {
//let r = R.unwrap_or(Fr::random(rng));
// c = g1^m1 * ... * gn^mn * h^r
let mut c = self.pub_bases[0].clone();
c.mul_assign(r.clone());
let mut c1 = self.pub_bases1[0].clone();
let mut c2 = self.pub_bases2[0].clone();
c1.mul_assign(r.clone());
c2.mul_assign(r.clone());
for i in 1..x.len() {
let mut basis = self.pub_bases[i];
basis.mul_assign(x[i]);
c.add_assign(&basis);
let mut basis1 = self.pub_bases1[i];
basis1.mul_assign(x[i]);
c1.add_assign(&basis1);
let mut basis2 = self.pub_bases2[i];
basis2.mul_assign(x[i]);
c2.add_assign(&basis2);
}
// return (c, r) <- r
Commitment { c: c }
Commitment { c1, c2 }
}
pub fn decommit(&self, cm: &Commitment<E>, x: &Vec<E::Fr>, r: &E::Fr) -> bool {
let l = x.len();
// pub_base[0] => h, x[0] => r
// check that cm.r == x[0]
let cr = r.clone();
let mut dc = self.pub_bases[0].clone();
dc.mul_assign(cr);
let mut dc1 = self.pub_bases1[0].clone();
let mut dc2 = self.pub_bases2[0].clone();
dc1.mul_assign(r.clone());
dc2.mul_assign(r.clone());
for i in 1..l {
let mut basis = self.pub_bases[i];
basis.mul_assign(x[i]);
dc.add_assign(&basis);
let mut basis1 = self.pub_bases1[i];
basis1.mul_assign(x[i]);
dc1.add_assign(&basis1);
let mut basis2 = self.pub_bases2[i];
basis2.mul_assign(x[i]);
dc2.add_assign(&basis2);
}
return dc == cm.c && cr == x[0];
return dc2 == cm.c2 && dc1 == cm.c1;
}
}
@ -178,7 +205,7 @@ mod tests {
for i in 0..len {
m.push(Fr::rand(rng));
}
let r = m[0].clone();
let r = Fr::rand(rng);
let c = csp.commit(rng, &m, &r);
assert_eq!(csp.decommit(&c, &m, &r), true);